The judge struck down Idaho‚??s same-sex marriage laws, which voters approved as an amendment to the state constitution in 2006. / Creatas Getty Images/Creatas RF

by Jens Manuel Krogstad, USA TODAY

by Jens Manuel Krogstad, USA TODAY

DES MOINES, Iowa -- The Iowa attorney general's office has appealed a court decision that overturned the animal torture conviction of a man who beat a puppy to death with a baseball bat.

Zachary S. Meerdink, 31, was convicted last year of killing his 7-month-old Boston terrier named Rocky in December 2011. The dog had made repeated messes on the floor and bit his girlfriend's children, court records show.

Two weeks ago, an Iowa Court of Appeals ruling tossed Meerdink's conviction. The three-judge panel voted 2-1 that prosecutors failed to prove Meerdink acted with a "depraved or sadistic intent to cause death," as required by the state's animal torture law. Evidence showed Meerdink did not appear happy about the beating, and had first tried other ways to change the puppy's behavior, the court's majority said.

State prosecutors, though, argued in an appeal filed Thursday with the Iowa Supreme Court that Meerdink did not have to look "happy or eager" to kill the puppy to be convicted of animal torture.

Further, there's no evidence the puppy had bitten anyone on the day of the deadly beating. Nor did it appear Meerdink had exhausted all other options: He had not finished reading a book about puppy training. It's also unclear why Meerdink did not take the dog to a pound or to a veterinarian to be euthanized in a humane manner, the state's appeal said.

"A rational fact-finder could also find that killing a seven-month-old puppy, without first finishing the training books or trying to find an alternative to death-via-baseball bat, is senseless," the appeal said.

The filing also asks the high court to clarify the state's animal torture law. Polk County Attorney John Sarcone told The Des Moines Register this month that the appeals court decision will make it harder to bring new animal torture cases in court.

State prosecutors called the death "brutal," noting the puppy's mangled body was found in tall grass near Meerdink's apartment.

Officials from St. Francis Foundation for Pets, a nonprofit in Des Moines, met with a state prosecutor Monday to make the case for an appeal, according to a letter from the group. The nonprofit cited statistics that show a significant number of people who abuse animals go on to abuse humans. "People are outraged at this appalling act of torture against an innocent dog and the incredulous decision handed down by the Court," the letter said.

The attorney general files five to 10 appeals each year with the Iowa Supreme Court, a spokesman for the office said.